WO2006042064A2

WO2006042064A2 - Composition inhibiting the expansion of fire, suppressing existing fire, and methods of manufacture and use thereof

Info

Publication number: WO2006042064A2
Application number: PCT/US2005/036073
Authority: WO
Inventors: James Alroy E. Hagquist; Robert M. Hume, Iii; Terrance L. Lund; Roderick I. Lund
Original assignee: Hagquist James Alroy E; Hume Robert M Iii; Lund Terrance L; Lund Roderick I
Priority date: 2004-10-11
Filing date: 2005-10-07
Publication date: 2006-04-20
Also published as: WO2006042064A3; US7163642B2; US7476346B2; US20070034823A1; US20060076531A1

Abstract

The invention relates to compositions that prevent expansion of a fire, suppress existing fire, as well as methods of preparing and using such compositions. The composition is comprised of water, pseudo-plastic high yield suspending agent and starch. Compositions may contain additional functional agents, such as rheological, wetting, foaming, coloring, chelating, antimicrobial and stabilizing agents. In the description of the present invention, all composition modifications are referred to as compositions. The composition, an augmentation of water, exhibits the characteristics of a sag resistant aqueous gel in the tank, but has shear thinning capacity, allowing the composition to be pumped or sprayed as easily as water. At the point of impact,. when the sprayed composition is again at rest, it instantly reverts to a sag resistant aqueous gel. The composition also forms an intumescent, surface char layer upon contacting a fire. Foaming of the augmented composition on impact can be incorporated, which is advantageous for fighting petroleum fires.

Description

COMPOSITION INHIBITING THE EXPANSION OF FIRE,

SUPPRESSING EXISTING FIRE, AND METHODS OF

MANUFACTURE AND USE THEREOF

CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY This application claims the benefit under 35 U.S. C. §119 (e) of co-pending provisional application Serial No. 60/617,616, filed 11 October, 2004. Application Serial No. 60/617,616 is hereby incorporated by reference.

STATEMENTREGARDINGFEDERALLYSPONSORED RESEARCHORDEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX, IF ANY Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention.

The present invention relates generally to the technical field of fire suppressant and fire

preventive compositions. More particularly, the present invention relates to an inventive aqueous

composition having unique properties and, most particularly, to an inventive aqueous

composition more effective than water alone for fighting fires.

2. Background Information.

Fire is a continuing danger to life and property worldwide. In rural areas forest, brush, and

grassland fires cause immense damage each year. This destruction is not only in terms of the

dollar value of timber, wildlife and livestock, but the catastrophic effects on erosion, watershed equilibrium and related problems to the natural environment. In urban areas, fire and the damage

from large quantities of water used to extinguish a fire is responsible for the destruction of

buildings with the loss of billions of dollars annually. Use of the composition of the present

invention to replace the water used to fight fires can reduce the total water consumption by up

to an order of magnitude. This reduction limits the damage caused by water in urban

manufacturing facilities, and other man-made structures. Most importantly, fire is a maj or danger

to human life. More quickly extinguishing a fire with the composition of the present invention

helps reduce the loss of life to fire.

Over the years man has found numerous methods for combating fires. The use of water,

foams, chemicals and other extinguishing materials are well documented. Water treated with a

wetting agent has been proven to be more effective on a Class A fire where good water

penetration is needed to reach and extinguish the seat of the fire. This concept is taught in U.S.

Pat. No.4,526,234 to Little. Antisettling or suspending agents are useful materials in controlling

powdered flame-retardants from settling or floating. This concept is taught in U. S. Pat. No.

5,374,687 to Cooperman et al. Efforts have concentrated not only on formulations and methods

for extinguishing a fire that is already in progress, but also for the prevention of fires by

pretreatment of combustible surfaces. This pretreatment coating can involve man-made

structures, such as buildings or storage tanks, or vegetation, such as fighting wild fires and

making fire lines or fire breaks.

Currently, there have been very substantial efforts in the area of pretreatment with

chemical retardants or suppressants. A number of these pretreatments have been developed and

used for fighting rural forest fires. For example, antimony oxide and its complexes, borates,

carbonates, bicarbonates, ammonium phosphate, ammonium sulfates, and other salts capable of

being hydrated, have been demonstrated to have useful properties as firefighting chemicals. Representative prior art patents teaching the use of chemical retardants were granted in the early

1900 ' s and continuing until more recent times. Such patents include; U.S. Pat. No.1 ,030,909 to

Mesturino; U.S. Pat. No.1,339,488 to Weiss; U.S. Pat. No 1,813,367 to Thompson; U.S. Pat. No. 2,875,044 to Dunn; U.S. Pat. No. 3,537,873 and U.S. Pat. No. 3,719,515 to Degginger; U.S. Pat.

No. 4,021,464 to Mayerhoefer et al; U.S. Pat. No. 4,076,580 to Panusch et al; and U.S. Pat. No.

4,095,985 to Brown. However, although the fire inhibiting properties of the borates, carbonates

and bicarbonates have been established, the use of these materials for vegetation fires has been

limited because of their tendency to inhibit plant growth when used in large quantities.

Recently, attention has turned to other chemical agents, such as the synergist combination

of antimony oxide and a halogen (fluorine, chlorine, bromine and iodine) or halogenated

compounds. Fire retardant formulations making use of these agents are taught in U.S. Pat. No.

3,196,108 to Nelson and U.S. Pat. No. 3,936,414 to Wright et al. See also Lyons, The Chemistry

and Uses of Fire Retardants, John Wiley & Sons, 1970 pages 147 and 411. Although extremely

effective in this usage, the usefulness of the antimony/halogen combination is partially limited

by the side reactions that may occur in a fire. Production of phosgene, diphosgene or chlorine gas

(WW I chemical war gases) and the generation of corrosive agents, such as inorganic acids from

ammonium phosphate and ammonium sulfate, requires the use of corrosion inhibitors to protect

the firefighting pumping equipment and the aluminum of an aircraft. These corrosion inhibitors

are expensive, sometimes toxic and increase the chance of environmental damage.

Another method of fighting fires is the pretreatment of flame-retardant materials on

combustible surfaces that lead to the creation of intumescent coating materials. Intumescent

materials expand with heat, similar to a vermiculite which expands when exposed to steam. The

expanded layer then protects the original surface from heat and flame. The problem is that an

expanded intumescent is also very fragile. This problem was soon realized, and the intumescent needed a protective hard outer coating. An intumescent ablative formulation answered this

challenge and is taught by U.S. Pat. No.6,716,485 B2 to Wong, et al. This lead to methods using

carbonaceous materials to form a char instead of the materials being consumed by the fire. The

making of carbonaceous chars is taught in many patents, including U.S. Pat. No. 6,696,030 Bl

to Hayden.

hi addition to all these problems, the most difficult problem to overcome for chemical

retardant formulations is that they are relatively expensive, compared to water. Also of concern

is the environmental impact of absorbent particles presently used in various gel formulations.

The absorbent particles pose an environmental risk once used to fight a fire, particularly when

used on a large scale, such as a forest fire. The cost factor also comes into conflict with applying

them in large quantities, as is often required. In combating or preventing forest, brush and grass

range fires, a considerable amount of effort has been spent in the search for low cost or waste

materials that are both available in quantity and inexpensive. One such low cost waste material

from the forest industry is lignosulfonates. Lignosulfonates are the sticking agent component in

many fire retardant formulations. Teaching the use of lignosulfonates as components in fire

retardant formulations include; U.S. Pat. No. 3,464,921 to Erler et al; U.S. Pat. No. 3,862,854

and U.S. Pat. No. 3,962,208 to Zeigerson et al; U.S. Pat. No. 3,915,911 to Horiguchi; U.S. Pat.

No.4,820,345 to Berg; U.S. Pat. No. 5,112,533 to Pope et al; U.S. Pat. No. 6,019,176 to Crouch

and U.S. Pat. No. 6;277,296B1 to Scheffee et al.

Applicants have devised a unique composition for fighting fires. In a preferred

embodiment, the composition consists of pseudo-plastic, high yield, suspending agent, plus

starch, both swelled and suspended, in water. The effectiveness of the inventive composition is

increased versus water alone. The composition forms a crust after making contact with a heat

source. After crusting over occurs, continued heating or burning near the compositions causes the crust to turn to a carbonized char. At this point, the composition consists of an outer coat of

char, which forms a hard, intumescent coating, and a soft interior of a gelled aqueous

composition. This synergist combination of hard shell protecting a soft interior gel, remains in

place until all the composition' s water has been evaporated. The composition functions as a heat sink, maintaining a substrate temperature below 100° C.

SUMMARY OF THE INVENTION

The invention is directed to compositions that are easily pumped or sprayed by high

pressure pumping equipment and/or that can be applied by small, low pressure, individual back

tanks that firstly, prevents the expansion of fire, secondly, suppresses existing fire and thirdly,

the present invention includes the methods of preparing and using such compositions.

The inventive compositions are used as an augmentation for water, and are

environmentally inert. The compositions have pseudo-plastic, high yield hydraulic properties

with a specific gravity very similar to water. The inventive compositions use pseudo-plastic high

yield suspending agents, starch, both swelled and/or suspended, rheology modifiers, wetting

agents, foaming or defoaming agents, coloring agents, antirricrobials and stabilizers added to

water to produce a stable, nonsettling composition that is easily pumped or sprayed and gives sag

resistance when applied on vertical or overhead surfaces. The inventive composition starves a

fire of its supply of fuel and cools the substrate surface. Wetting agents help the composition

penetrate into porous combustible surfaces and, with a unique combination of suspending agent

and starch, resist the exiting of water via means of tack and rheology. The unique composition

containing pseudo-plastic high yield suspending agent and suspended starch results in a

composition that is shear thinning and, therefore, can be sprayed into a fire, with the composition

holding instantly on vertical or overhead surfaces. Then, as heat from the fire raises the temperature of the composition driving off more water, the composition swells and associates

more starch, raising the viscosity and making the composition even more resistant to flow.

Commonly, water is used to reduce heat and suffocate a fire, but this only occurs while

the water coats the combustible surface. Typically, more than 95% of the water is lost

immediately from vertical or overhead surfaces due to gravity, as depicted in Figure 1. At this

point, water loses its ability to fight the fire as it runs down the wall of a building or off the

vegetation of a field or forest and into the soil. The inventive composition, with its unique

combination of starch and high yield suspending agent, when exposed to the heat of a fire, does

not lower in viscosity and run off, but actually increases in viscosity and becomes more tacky.

Therefore, much less of the inventive composition is needed to fight the fire. Firefighting

personnel now have the ability to coat a surface with a layer of augmented water, an aqueous gel

of the inventive composition, which becomes stickier and more thixotropic the instant it is

exposed to heat. The inventive composition eventually forms a crust as the surface dries, which

is, in turn, carbonized to a char forming, intumescent coating, remaining in place regardless of

the orientation of the substrate, as depicted in Figure 2. The inventive composition uses less

water to control or extinguish a fire, thereby reducing the damage caused by the run off of water

after the fire is extinguished.

When applied to a fire, the inventive composition takes two forms. On the surface is the

thin hard carbonized char, forming the intumescent layer and below is a sticky, thick, aqueous

gel which makes up the majority of the composition. The char helps reduce the moisture loss

from the aqueous gel of the composition and prevents the fire from reaching additional

combustible substrates. The coated combustible substrate temperature now cannot exceed the

boiling point of water (100° C), until the aqueous gel of the composition is fully dried.

A liquid concentrate of the inventive composition is made with a simple mixer. In the mixer combine water, wetting agent, pseudo-plastic suspending agent and any known starch

(amylose and amylopectin) from corn, wheat, potato, tapioca, barley, arrowroot, or rice and/or

any combination of starches blended together. A dry powder blend can also be made starting with

a powdered wetting agent, then adding a dry pseudo-plastic suspending agent and then adding

dry powdered starch. The use of suspending agents or antisettling agents helps maintain a stable

liquid mixture. The pH of the inventive composition is preferably adjusted to the range of about

5.0-8.0. A buffering agent, such as Advantex, available from Arkema Corp., composed of liquid

amino alcohol, can be used to effect pH adjustment. Alternatively, simple caustic (NaOH) is used

for pH adjustment. Addition of some wetting agent speeds up the mixing process and also allow

the composition to better wet out combustible substrates during its use to fight fires. Examples

of wetting agents include the biodegradable Triton X-100 (octylphenol ethoxylate), available

from Dow Chemical Surfactants. Other elective components can be added to the inventive

composition to achieve unique desired characteristics. For example, foaming agents are added

to compositions for the fighting of petroleum fires, coloring agents are added to compositions

to help distinguish between various composition formulations. For example, one color

composition is formulated for fighting brush fires and another color composition is specifically

for fighting urban building structures. Examples of foaming agents include liquid detergent,

liquid soap, and AFFF (aqueous film forming foam) composed of diethylene glycol monobutyl

ether, hydrocarbon surfactant, fluorocarbon surfactant, polysaccharide gum and magnesium i sulfate. Coloring agent examples include water soluble food grade dyes, such as Red #40, Allura

Red AC, an Orange/Red dye, Blue #2 Indigotine, Royal Blue Dye, Green #3, Fast Green FCF,

a Sea Green dye.

hi some instances, a defoaming agent is required for the inventive composition.

Examples of defoaming agents include the silicone formulations DC- 1520, FG- 10 and FC-4330, available from Dow Corning. A nonionic defoaming agent suitable for preventing environmental

degradation is Foamaster A-7.

Antimicrobials and stabilizers are added to the inventive composition to protect

surrounding buildings from mold and extend the shelf life of the inventive composition, as well

as protecting soils from the catastrophic effects of erosion and watershed equilibrium. Examples

of antimicrobial agents include blends of methyl paraben and propyl paraben, and Vancide # 51,

a blend of sodium dimethyldithiocarbamate and sodium 2(3H)-benzothiazolethione. Stabilizer

examples include a fumed silica, such as Carb-O-Sil, or a borate. To fight fires where an extreme

need to extinguish the fire in seconds is more important then toxicity concerns, conventional fire

retardants such as halogens, antimony oxide and salts, such as ammonium phosphate, ammonium

sulfate or other similar chemical retardants, can be used as modifiers that are easily added and

then utilized with such special compositions.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross sectional view of vertical and horizontal substrates within a fire

following application of water alone.

Figure 2 is a cross sectional view of vertical and horizontal substrates within a fire

following application of the inventive composition of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The invention relates to compositions that are augmentations to water, either from

concentrate or dry blends, used to extinguish fires. The concentrate or dry blend is added to a fire

fighter's water reservoir and simply stirred in or allowed to recirculate. These compositions use

pseudo-plastic high yield suspending agents, plus starch, both swelled and suspended, rheology modifiers, wetting agents, foaming agents, coloring agents, antimicrobials and stabilizers, added

to water to produce a stable, nonsettling augmentation to water. The water augmentation, an

aqueous gel of the inventive composition, is easily pumped or sprayed by typical high pressure

pumping equipment or by low-pressure individual back tanks. The composition has a "high yield

value," meaning it has an initial resistance to flow under stress but then is shear thinning, and

when used, exhibits "vertical cling," meaning it has the ability at rest, to immediately return to

a thixotropic gel. A firefighter now has a material that does not separate or settle, can be easily

sprayed and immediately thickens when it contacts a wall or ceiling surface. This gives the

firefighter the ability, unlike water alone, to build thickness and hold the aqueous gel of the

inventive composition on vertical or overhead surfaces. The aqueous gel of the composition's

mass and the vertical cling both acts as a heat sink capable of clinging to vertical and overhead

surfaces. This clinging to the surfaces causes the overall temperature of the surfaces to remain

below the boiling point of water. The heat sink effect does not allow the temperature of the

surface coated with the aqueous gel of the composition to exceed 100° C until all the water in the

composition has been evaporated. To produce this shear thinning effect and then cling, the composition uses a pseudo-plastic high yield-suspending agent.

There are many types of pseudo-plastic Jiigh yield suspending agents or rheology

modifiers that can be used successfully in the inventive composition. Two of the major groups

of such suspending agents are laponites, a synthetic smectite clay, and Carbopols®, generally

high molecular weigh homo- and copolymers of acrylic acid cross linked with a polyalkenyl

polyether. Other polymers and synthetic clays are suitable and may be used in combination to

develop special pseudo-plastic high yield suspending agent characteristics. In using a

combination of these suspending agents, synergism is found, for example, between laponites and

Carbopols®, where a blend offers improved characteristics for the composition. Of the group of laponites, which are synthetic smectite clays closely resembling the natural clay mineral

hectoritic, it was found that Laponites RD and RDS provide the best performance. Laponites RD

and RDS are layered hydrous magnesium silicates that disperse rapidly in water without the need

for high shear. Laponites RD and RDS are manufactured by Southern Clay Products, Inc.,

Gonzales, TX 78629, and are commercially available from Fitz Chemical Corporation, Itasca,

IL 60143. Laponite RDS at a concentration of about 0.001-2.0 % is ahighly effective rheology

modifier. Laponite RDS at a concentration of about 0.1-0.5 % is a preferred rheology modifier.

In another major group of suspending agents, the Carbopols®, one particularly effective material

is Carbopol® EZ-3 , a hydrophobically modified cross-linked polyacrylate powder. The polymer

is self- wetting and requires low agitation for dispersion. The convenience of low agitation is

very evident in the very short wetting out time needed, when making a concentrate. Carbopol®

EZ-3 is commercially available from Noveon, Inc., Cleveland, Ohio 44141. Carbopol® EZ-3

at a concentration of about 0.001-2.0% provides acceptable performance. Carbopol® EZ-3 at

a concentration of about 0.01-1.0 % is a preferred rheology modifier. A blend of Carbopol® EZ-

3 and Laponite RDS in the range of about 0.002-4.0 % each is the most preferred rheology

modifier combination. Preferably, the Carbopol® EZ-3 and Laponite RDS are present in

approximately equal amounts, by weight, in the inventive composition. Both of these materials

hold solid particles in suspension without allowing the solids to settle. Both of these materials

have a shear thinning rheology so they can be pumped or sprayed onto a surface without the loss

of cling. The Carbopol® EZ-3 is the more efficient of pseudo-plastic high yield suspending

agents tested and the Laponite RDS one of the fastest to build in viscosity, as tested after shear

thinning. The laponites are especially sensitive to electrolytes or the typical salts in water. Many

pseudo-plastic high yield suspending agents need to be fully dispersed and hydrated in water to

achieve the best performance characteristics. The inventive composition improves the overall efficiency of putting fire out with water. Other suitable pseudo-plastic, high yield, suspending

agents include casein, alginates, modified cellulose, including methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and carbomethyl cellulose, gum tragacanth used individually

or in combination. The method of preparing and making antisettling mixtures of the inventive

composition in water is a unique combination of suspending agent and swelled or suspended

starch.

If each component of this unique mixture of suspending agent and starch in this

composition were used separately, the ability to fight a fire would be drastically reduced. Using

just the pseudo-plastic high yield suspending agent would mean the material could be pumped

and that it would have cling to hold it to vertical and/or overhead surfaces. Although, the pseudo-

plastic high yield-suspending agent is temperature stable, meaning the viscosity does not decrease

as the temperature rises, the heated material would have an accelerated evaporation rate. There

is no means to slow down the evaporation of the water, such as a crust or char, which forms with

starch included in the inventive composition. If, on the other hand, only starch was present, the

composition would hard settle in the tanks, pipes and hoses, and if it could be used, the starch

composition would not cling to vertical surfaces. If some of the starch is preheated to swell, this

increases the clinging ability of the composition, but the viscosity is now so high that it is be

impossible for this starch composition to be pumped or sprayed.

The unique mixture in the inventive composition of pseudo-plastic high yield suspending

agent and hydrated starch provides a composition in which the starch does not settle, even on

aging. The inventive composition has a high yield value with a "shear thinning capacity" which

means, the composition becomes thin when pumped and instantly thixotropic or sag resistant,

at rest. Thus, after being pumped and sprayed, the composition is capable of clinging to a vertical

or overhead surface. In the inventive composition, any starch can be used. Examples of typical starches include corn, wheat, potato, tapioca, barley, arrowroot, rice or any combination of

starches. Another example is Fiber-Star P, a preboiled potato starch. This list is not an attempt

to limit the number of starches, but to demonstrate that all starches function in this composition

to varying degrees. It is contemplated that various, starch precursors are also functional in the

present inventive composition. The amount of starch used varies, depending on particular

characteristics needed for the composition. Formulas can vary in starch content from about 0.01-

20.0 wt %. Preferably, a starch content from about 0.05-10 wt % is preferred, and most

preferably, the composition has a starch content from about 0.1-2.0 wt %. In a preferred

embodiment of the inventive composition, the suspending agent and starch components

combined, preferably comprise no more than about 1.00 wt % of the aqueous, thixotropic

composition. In a most preferred embodiment of the inventive composition, the suspending

agent and starch components combined, preferably comprise no more than about 0.50 wt % of

the aqueous, thixotropic composition.

A rheology modifier can also affect starches. The rheology modifier, borate, is used in

the composition to add cross linking. Additional value from the borate is that borate is an

excellent flame retardant by itself. Commonly, borates are used as modifiers for wetting agents

in soaps or washing powders.

Dry starch originally contains about 12% water and has a particle size of 20 microns.

When soaked in water, the starch associates and holds up to 18% water and the particle size

increases to 40 microns. As the starch/water mixture is heated, in this case by a fire, the starch

forms a gel or association with all the surrounding water starting around 160° F (71° C). Thus,

when the composition is heated, either from the substrate or the air side, the starch absorbs more

water at the interface and becomes thicker. On the substrate side, the composition first rides on

its own vapor and, as it cools, forms its own film on the substrate surface. On the air side, where evaporation largely occurs, the composition tirst tnicKens and then crusts over and eventually is

converted to a carbonized char. The char formed is a hard, intumescent coating, which slows the

evaporation of water from the composition, as illustrated in Figure 2. In essence, the

composition's own film and char act as a vessel to contain the soft-gelled composition, which

now acts as a heat sink to cool the backside of the intumescent char. This synergism between

the intumescent hard coating and the composition's aqueous gel helps optimize a very limited

amount of water. The char/gel coating further reduces the available combustible material to the

fire, and also reduces the smoke emission. There are no dangerous chemical reactions caused by

the application of the inventive composition and its byproducts are neither corrosive nor toxic.

Other components can be added to the composition to enhance a desired property, a foaming

agent, such as commercially available liquid detergent or liquid soap, being a good example.

Example of GeI Preparation

Four (4) gallons (15,000 grams) of tap water were placed in a 10-gallon container.

Seventy-six (76) grams of Carbopol® EZ-3 and seventy-six (76) grams of corn starch were

stirred into the water. At this point, the composition had a pH less than 2.5. The pH was

adjusted to between 5.5 and 7.0 by adding 10 grams of sodium hydroxide. The composition

exhibited shear thinning characteristics but was too thick to be pumped. An additional 2 gallons

(7,500 grams) of tap water were added to the container to provide a pumpable composition with

suitable thixotropic and shear thinning properties. The components making up the composition

on a wight/weight basis are: Carbopol® EZ-3 - 0.335%; corn starch - 0.335%; sodium

hydroxide - 0.044% and water - balance (99.285%).

Li the past, when fire fighters were only using water, many times smoldering embers

harbored a fire on the inside of a log or limb that later rekindled the fire. With the inventive composition, the combination of an aqueous gel sticking to the charred surface and a wetting

agent, which allows it to penetrate into the cracks, gives the fire fighter a much greater chance

of extinguishing the fire with no recurrence after the initial contact. The aqueous gel created by

the inventive composition contains more than 90% water. This high water yield keeps water

where the fire fighter has placed it. The composition reduces the amount of water used and

provides increased fire suppression potential per gallon of water. Further, because of the

composition's aqueous gel characteristics, the immediate seepage through floors and walls by

water is reduced. The water in the composition, now coating and sticking to combustible

materials, does not separate in the fire, nor does the water making up the composition drain away.

More than 95% of the water used by fire fighters is typically lost immediately from vertical or

overhead surfaces due to runoff. The inventive composition both extinguishes existing fires and

suppresses rekindling of hot substrate.

Water Yield:

To provide a quantitative measure of the increased ability of the composition of the

present invention to hold water to a potentially combustible surface, a water yield test was

performed. This test compared composition No. 1, described below, to water. Small wooden

strips were vertically dipped to an equal depth in either water or composition No. 1. The wooden

strips were weighed before and after dipping to determine the amount of water retained on each

strip. One strip dipped into water retained 0.13 grams of water. The strip dipped into

composition No. 1 retained 6.93 grams of the aqueous composition. Thus, composition No. 1

retains fifty-three (53) times the water weight on the wooden strip compared to water alone.

In an attempt to maximize the vertical holding capability and minimize the problems that

occur in pumping or handling thick materials, a series of decreasing concentrations of suspending agents/starch compositions were evaluated for their ability to hold on a vertical surface. The

same compositions were then compared for their ability to resist fire and heat. As an initial point

Composition No. 1, with suspending agent and starch at approximately 0.50 % each, was used.

Five (5) dilutions of Composition No.1 were then made. Composition No. 14 has about 8.3%

less suspending agent and starch. Composition No. 15 has about 16.6% less suspending agent

and starch. Composition No. 16 has about 23% less suspending agent and starch. Composition

No. 17 has about 28.6 % less suspending agent and starch. Composition No. 18 has about 33.3

% less suspending agent and starch. The components of each composition are summarized in

Table 1 below.

TABLE 1

PERCENTAGE BY WEIGHT OF COMPONENTS IN THIXOTROPIC

COMPOSITION

Ingredient Component No. 1 No. 14 No. 15 No. 16 No. 17 No. 18

Suspending Carbopol 0.5013 0.4557 0.4177 0.3856 0.3580 0.3342 Agent EZ-3

Starch corn starch 0.5013 0.4557 0.4177 0.3856 0.3580 0.3342 pH sodium 0.066 0.060 0.055 0.051 0.047 0.044 Modifier hydroxide

Water water 98.9316 99.0287 99.1096 99.1781 99.2368 99.2877

Droop Test;

The above-described compositions were further evaluated for the ability to remain in

place when applied to either vertical or overhead surfaces. The clinging ability is measured by

the droop test. A cylindrical hole is provided in a 1/4 inch thick pine board. The board is placed on a horizontal flat surface and the hole filled with the test composition and leveled with a

straight edge. The board is then turned 90 degrees such that the open end of the cylindrical hole

is on a vertical surface. The distance that the composition flows downwardly on the vertical

surface of the board is determined after a specified time period. The results are tabulated in

Table 2.

Char and Burn Through Tests:

These same modified compositions were evaluated by comparing their ability to resist

the spread of fire, first on a room temperature (RT) pine wood substrate and second on a

preheated, hot pine wood substrate. In this test a 1800° F propane torch heat source was applied

5 inches from a paddy formed by a stencil 1/8 inch thick and 2 inches in diameter of each

composition. When tested, the paddies were held in a vertical position. Before starting the initial

test, the heat source was applied to just the pine wood without any protective coating, The

combustible pine wood burst into flames in less then 5 seconds. In a comparison of time to first

char, all paddies were very similar and the first char occurred around 30 seconds. In a comparison

of burn through, another interesting fact appeared. The initial composition, No. 1, and the next

two dilutions, No. 14 and No. 15, had approximately the same time to burn through,

approximately two (2) minutes. The difference in the next three dilutions appears to be caused

by droop. Under flame, the thinness of the paddy allowed the flame to burn through more

quickly. If a preheated substrate is used (simulates being on fire) almost all dilutions of the

original compositions burned through in the same time if enough preheat had been applied, as

seen in Table 2. TABLE 2 FIRE, HEAT AND DROOP TESTING OF THIXOTROPIC COMPOSITION

Composition Number No. 1 No. 14 No. 15 No. 16 No. 17 No. 18 Droop Test Initial Weight, Ib. 0.185 0.205 0.225 0.250 0.265 0.290

Droop Test Dist, inches 1.75 2.42 2.70 3.10 3.85 5.30 Burn Test at Room T

First Char, minutes 0:30 0:30 0:30 0:30 0:30 0:24

Burn Through, minutes 2:15 1:50 2:09 1:00 0:49 0:24 Burn Test at Elevated T

First Char, minutes 0:30 0:30 0:30

Burn Through, minutes 2:20 2:07 0:30

When using the inventive composition to fight a large industrial or commercial fire, water

and mold damage after the fire is extinguished is another big issue. The damage to buildings

unassociated with the those involved in a fire has become a billion-dollar insurance loss, in

addition to a maj or health problem to future occupancy of these b uildings . Reducing the quantity

of water needed to fight a fire by increasing the efficiency of the composition to extinguish a fire,

as well as the addition of antimicrobials agent to the composition, reduces the impact on all

structures.

In comparison to a standard fire fighting foam, the inventive composition has some

important differences. The aqueous gel of the composition has the advantage of mass from the

high water yield. Fire fighters using a standard foam see the foam quickly evaporating or being

broken down, either by radiant heat or direct flame contact. With the high water yield of the

inventive composition, greater tolerance to the heatand flames is exhibited, and the composition

can be applied in only one step versus the required two steps of most foams. Optionally, a foaming additive can be added to the inventive composition to fight fires

where the inventive composition needs to float. This feature is particularly useful in fighting oil,

gasoline or petroleum fires. Without the foaming of the composition, the composition sinks and

it is of little value in extinguish the petroleum fire. Another modification includes a simple color-

coding to indicate a particular modification of the composition. Addition of a coloring agent to

the composition provides facile identification of specific formulations. The color-coding feature

minimizes the chance of using the wrong composition for a particular application.

One of the compositions greatest asset is its increased safety feature. The composition's

aqueous gel is easily sprayed or pumped like water, but can be projected greater distances than

water alone. This allows attack of the fire from an increased distance and reduces the risk to a

fire fighter or fire fighting aircraft. The pseudo-plastic, high yield characteristics of the composition cause the material to disperse in small clusters when projected, versus breaking into

a mist. This characteristic is advantageous when dropping material from aircraft onto a fire. The

composition's aqueous gel also reduces the potential for flashover because of its ability to stay

on a surface, maintain a water yield and disrupt the thermal layers on a structure's ceiling and

walls during initial attack of a fire. Fires spread very rapidly. It's commonly known that a fire

doubles in size every minute during the beginning of a burn, so the more quickly the fire is under

control, the less danger there is for the fire fighters.

The inventive composition also finds many other applications. Several of its potential

uses include fire breaks sprayed down for forest fires and back fires, application to protect

homes, businesses and fuel storage tanks, and less water usage allowing one truck to provide

significantly greater fire suppressant capabilities.

In addition, the inventive composition does not make a surface slipperier than water, but

a thick coating could give buoyancy. Another potential use includes the coating of fruit trees to protect them from frost. Likewise, the filling of rodent holes with the gel under pressure, thus

filling all tunnel voids or cavities, makes the tunnels useless to the rodent. Such uses cause no

detrimental effects to the surrounding environment.

It is contemplated that salt water (brine) can be used in place of fresh water when

preparing the composition of the present invention. Special pseudo-plastic, high yield

suspending agents, which form gels that are nonsensitive to salts, are required when using salt

water or brackish water.

While the invention has been particularly shown and described with reference to preferred

embodiments thereof, it will be understood by those skilled in the art that various changes in

form and details may be made therein without departing from the spirit and scope of the

invention.

Claims

We claim:

1. An aqueous, thixotropic composition having shear thinning properties for fire suppression and prevention comprising:

0.001 to 2.0 wt % of a pseudo-plastic, high yield, suspending agent;

0.01-20.0 wt % of starch; and

the balance being water;

the composition adjusted to a pH in the range of about 5.0-8.0;

whereby the composition clings to a surface positioned in any orientation, and forms an

exterior intumescent char coating upon fire contact, while retaining an interior aqueous gel

composition, thereby extinguishing a fire and preventing rekindling thereof.

2. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 1, wherein the pseudo-plastic, high yield, suspending agent is selected

from the group consisting of; acrylic acid copolymer cross linked with a polyalkenyl polyether,

synthetic smectite clay, casein, alginates, modified cellulose, including methyl cellulose,

hydroxyethyl cellulose, hydroxypropyl cellulose and carbomethyl cellulose, gum tragacanth and

combinations thereof.

3. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 1 , wherein the starch is selected from the group consisting of corn starch,

wheat starch, potato starch, tapioca starch, barley starch, arrowroot starch, rice starch and

combinations thereof.

4. The aqueous, thixotropic composition having shear thinning properties' for fire suppressant

and prevention of claim 1, further including at least one component selected from the group

consisting of a surfactant or wetting agent, a chelating agent, a conventional fire retardant, apH buffering agent,

a coloring agent, an antimicrobial agent, a foaming agent, a defoaming agent, and a film forming

agent.

5. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 1, wherein the suspending agent and starch components combined

preferably comprise no more than about 1.00 wt % of the aqueous, thixotropic composition.

6. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 1 , wherein the suspending agent and starch components combined most

preferably comprise no more than about 0.50 wt % of the aqueous, thixotropic composition.

7. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 1, wherein the suspending agent and starch components are present in

approximately equal amounts, by weight, in the aqueous, thixotropic composition.

8. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 1, wherein the pseudo-plastic, high yield, suspending agent comprises

a mixture of an acrylic acid copolymer cross linked with a polyalkenyl polyether and a synthetic

smectite clay.

9. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 8, wherein the acrylic acid copolymer cross linked with a polyalkenyl

polyether and the synthetic smectite clay are present in approximately equal amounts, by weight,

in the aqueous, thixotropic composition.

10. An aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention comprising:

0.01 to 2.0 wt % of a pseudo-plastic, high yield, suspending agent comprising a mixture

of an acrylic acid copolymer cross linked with a polyalkenyl polyether and a synthetic smectite

clay;

0.01-2.0 wt % of starch; and

the balance being water;

the composition adjusted to a pH in the range of about 5.0-8.0;

composition, thereby extinguishing a fire and preventing rekindling thereof.

11. The aqueous, thixotropic composition having shear thinning properties for fire suppressant

and prevention of claim 10, further including at least one component selected from the group

consisting of a surfactant or wetting agent, a chelating agent, a conventional fire retardant, a pH

buffering agent,

agent.

12. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 10, wherein the suspending agent and starch components combined

13. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 10, wherein the suspending agent and starch components combined most

14. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 10, wherein the suspending agent and starch components are present in

15. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 10, wherein the acrylic acid copolymer cross linked with a polyalkenyl

in the aqueous, thixotropic composition.

16. An aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention comprising:

0.01 to 2.0 wt % of a pseudo-plastic, high yield, suspending agent comprising an equal

weight mixture of an acrylic acid copolymer cross linked with a polyalkenyl polyether and a

synthetic smectite clay;

0.01-2.0 wt % of starch; and

the balance being water; the composition adjusted to a pH in the range of about 5.0-8.0;

composition, thereby extinguishing a fire and preventing rekindling thereof.

17. The aqueous, thixotropic composition having shear thinning properties for fire suppression

and prevention of claim 16, wherein the suspending agent and starch components are present in

approximately equal amounts, by weight, and combined most preferably comprise no more than about 0.50 wt % of the aqueous, thixotropic composition.

18. The aqueous, thixotropic composition having shear thinning properties for fire suppressant

and prevention of claim 16, further including at least one component selected from the group

buffering agent, a coloring agent, an antimicrobial agent, a foaming agent, a defoaming agent,

and a film forming agent.

19. A method of extinguishing or suppressing a fire comprising;

providing a thixotropic, fire fighting composition having shear thinning properties

comprising water, a pseudo-plastic, high yield, suspending agent, and starch, the composition

adjusted to a pH in the range of about 5.0-8.0; and

applying the composition to an area where extinguishment or suppression of the fire is

desired, whereby the composition clings to a surface positioned in any orientation, and forms an exterior intumescent char coating upon fire contact, while retaining an interior aqueous gel

composition, thereby extinguishing a fire and preventing rekindling thereof.

20. The method of claim 19, wherein the composition includes a foaming agent, thereby

enabling the composition to float on a hydrocarbon liquid and extinguish a petroleum fire.